StrangeTools/DummyCursor/Spy/WndFinder.cs

using System.Runtime.InteropServices;
using System.Text;

namespace DummyCursor.Spy
{
    internal class WndFinder
    {
        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        private static extern int GetWindowText(IntPtr hWnd, StringBuilder strText, int maxCount);

        [DllImport("user32.dll", CharSet = CharSet.Unicode)]
        private static extern int GetWindowTextLength(IntPtr hWnd);

        [DllImport("user32.dll")]
        private static extern bool EnumWindows(EnumWindowsProc enumProc, IntPtr lParam);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool EnumChildWindows(IntPtr hwndParent, EnumWindowsProc lpEnumFunc, IntPtr lParam);

        // Delegate to filter which windows to include
        public delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);

        /// <summary> Get the text for the window pointed to by hWnd </summary>
        public static string GetWindowText(IntPtr hWnd)
        {
            int size = GetWindowTextLength(hWnd);
            if (size > 0)
            {
                var builder = new StringBuilder(size + 1);
                GetWindowText(hWnd, builder, builder.Capacity);
                return builder.ToString();
            }

            return String.Empty;
        }

        /// <summary> Find all windows that match the given filter </summary>
        /// <param name="filter"> A delegate that returns true for windows
        ///    that should be returned and false for windows that should
        ///    not be returned </param>
        public static IEnumerable<IntPtr> FindWindows(EnumWindowsProc filter)
        {
            List<IntPtr> windows = new List<IntPtr>();

            void EnumChild(IntPtr hWnd, IntPtr lParam)
            {
                EnumChildWindows(hWnd, delegate (IntPtr hWndChild, IntPtr lParamChild)
                {
                    if (filter(hWndChild, lParam))
                    {
                        // only add the windows that pass the filter
                        windows.Add(hWndChild);
                    }

                    EnumChild(hWndChild, lParamChild);

                    return true;
                }, IntPtr.Zero);
            }

            EnumWindows(delegate (IntPtr wnd, IntPtr param)
            {
                if (filter(wnd, param))
                {
                    // only add the windows that pass the filter
                    windows.Add(wnd);
                }

                EnumChild(wnd, param);

                // but return true here so that we iterate all windows
                return true;
            }, IntPtr.Zero);

            return windows;
        }

        /// <summary> Find all windows that contain the given title text </summary>
        /// <param name="titleText"> The text that the window title must contain. </param>
        public static IEnumerable<IntPtr> FindWindowsWithText(string titleText)
        {
            return FindWindows(delegate (IntPtr wnd, IntPtr param)
            {
                return GetWindowText(wnd).Contains(titleText);
            });
        }
    }
}